William Steck performed under some of the most eminent conductors of the latter 20th century. Here, Steck plays a violin solo at the Kennedy Center. (Dudley M. Brooks/The Washington Post)

William Steck, a violinist who performed under some of the most eminent conductors of the latter half of the 20th century and served as concertmaster of the National Symphony Orchestra for nearly two decades, died April 13 at Inova Mount Vernon Hospital. He was 79.

His death, from respiratory failure, was confirmed by his wife, Ann Steck.

From his appointment as concertmaster in 1982 until he stepped down in 2001, Mr. Steck was a familiar and essential presence at NSO performances at the Kennedy Center in Washington and on tours around the world.

Violin in hand, he would appear on stage after other orchestra members had taken their seats. He would face the audience, bow on behalf of the ensemble, then turn to his colleagues to begin a rite of orchestral performance: the oboe’s sounding of a pure A and the tuning of each section in turn. The conductor would then stride toward the podium and shake hands with Mr. Steck, and the music would begin.

A concertmaster is second in importance only to the conductor. While an in-demand conductor may lead his or her orchestra in only a portion of its concerts over a year, the concertmaster is almost always present. The duties are wide-ranging and include acting as a liaison with the musical director, lassoing the often wild strings section and — perhaps most immediately important to audiences — performing violin solos.

Mr. Steck “plays with excellent technique and beguiling lyricism,” Washington Post staff writer Joseph McLellan wrote in 1986. “His cadenzas, with the orchestra silent, are graceful and beautifully formed, and they probe deeply into the inner workings of the music.”

Mr. Steck was brought to Washington by Mstislav Rostropovich, the celebrated cellist-conductor who served as NSO music director from 1977 to 1994. Dozens of violinists had tried out for the job, but “Slava” found none who met his standards — until the NSO leadership flew Mr. Steck to Paris to meet him for an audition.

Mr. Steck learned of his selection when Rostropovich introduced him to a Parisian concert hall manager as “the new concertmaster of the National Symphony Orchestra.” “That’s how I found out,” Mr. Steck once told The Washington Post.

He had an impeccable musical pedigree. In the early 1960s, he was a violinist with the Philadelphia Orchestra under Eugene Ormandy. He graduated to assistant concertmaster positions with the Philadelphia Chamber Symphony and then the Cleveland Orchestra under George Szell and later Lorin Maazel.

In the 1970s, Mr. Steck scored his first appointments as concertmaster with the Dallas Symphony Orchestra under Max Rudolf and the Atlanta Symphony Orchestra under Robert Shaw. After Rostropovich left the NSO, Mr. Steck continued as concertmaster under Leonard Slatkin.

Vern William Steck was born Feb. 18, 1934, in Powell, Wyo. He was encouraged almost from birth to pursue music: His father was a violinist who had returned to his family’s farm during the Depression, and his mother held a variety of jobs to finance their only child’s musical education.

At times, the parents were forced to choose between buying their son new toys and taking him to concerts by such violinists as Jascha Heifetz and Yehudi Menuhin.

The family settled in Philadelphia, where Mr. Steck studied at the Curtis Institute of Music. He graduated from the Philadelphia Musical Academy in 1952 and received a master’s degree in music from the University of Texas at Austin in 1957.

In addition to his work with the NSO, Mr. Steck gave violin lessons from his home in Alexandria for 30 years until shortly before his death. He played in a number of recordings, including several by the NSO.

His first marriage, to Dixie Grace Steck, ended in divorce. Survivors include his wife of 37 years, Ann Pinney Steck of Alexandria; three children from his first marriage, William S. Steck of San Jose, Costa Rica, Allegra Steck of Staunton, Va., and Randall Steck of Alexandria; and three grandchildren.

In an interview, Vernon Summers, a longtime first violinist with the NSO, recalled Mr. Steck’s description of a concertmaster’s job. He said that he needed three eyes: one for the conductor, one for his music and one for the fiddles around him.